1. Field of the Invention
The present invention relates to a printer system that performs image printing using a plurality of print heads having a plurality of nozzles for discharging ink droplets.
2. Related Art Statement
Conventionally, as a color inkjet printer that uses a plurality of print heads, each print head being assigned one color and having a plurality of nozzles for discharging ink droplets, a head-scan color inkjet printer that performs color printing by causing the plurality of print heads to scan in a direction perpendicular to the paper feeding direction has been available.
Meanwhile, in recent years, what is called a head-non-scan one-pass inkjet printer has been proposed. In this printer, print head groups are configured such that a plurality of print heads having rows of nozzles is arranged in the paper width direction. The print head groups are provided so as to correspond to the number of colors to be used, each print head group being assigned one color. With this arrangement, the printer performs high-speed printing by feeding only paper in one direction without causing the head to scan.
However, in general, inkjet printers become more difficult to manufacture and more expensive as the number of rows of nozzles increases. Thus, a width that can be printed by a single head used in the head-non-scan one-pass inkjet printer is not much different from a width that can be printed with one scan by a head used in the head-scan inkjet printer. As a result, with the head-non-scan one-pass inkjet printer, when the paper width is increased from A4 size to A3 size (JIS standard) . . . , or the number of ink colors is increased, the number of print heads used is significantly increased.
Since the head controllers for the discharge of ink from the print heads in the conventional scan-type inkjet printer only control, for example, four print heads for four colors, they do not have a particularly complicated structure. However, with the non-scan inkjet printer, which uses the plurality of print head groups constituted by the plurality of print heads, the positions of data corresponding to the rows of nozzles which are read from a buffer memory need to be changed so as to correspond to the intervals of the rows of nozzles in a large number of heads. In addition, since the number of print heads is greater than that number of printer heads in the scan-type inkjet printer, the capacity of the buffer memory is increased correspondingly.
As a result, there is a need for changing the pointer in the memory for each of the large number of the rows of nozzles (for each print head) by using a large-capacity buffer. Thus, when a single head controller needs to be used for the large number of print heads, there is a problem in that the control becomes significantly complicated.
In particular, with the non-scan inkjet printer that uses the large number of print head groups, since the print head groups for individual colors are arranged with a certain distance therebetween with respect to the paper feeding direction, there is a possibility that image-printing positions are displaced between print head groups due to an error in a scale pitch, which is a reference for the discharge timing. Thus, the image-printing accuracy may be adversely affected.